Epha2 genotype influences ultraviolet radiation induced cataract in mice

Famine exposure in early life increases risk of cataracts in elderly stage

Background

Epidemiological studies have shown that early-life nutritional deficiencies are associated with an increased risk of diseases later in life. This study aimed to explore the correlation between famine exposure during the early stages of life and cataracts.

Methods

We included 5,931 participants from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) 2018 cross-sectional data in our study. Subjects were categorized into three groups by their age during the famine: adulthood group, school age famine exposure group, and teenage famine exposure group. Utilizing binary logistic regression models, we investigated the relationship between early-life famine exposure and cataracts.

Results

Compared to the adulthood group, both the school age exposure group (OR = 2.49, 95%CI = 1.89-3.27) and teenage exposure group (OR = 1.45, 95%CI = 1.20-1.76) had a heightened risk of developing cataracts in elderly stage. And the sex differences in the impact of famine during early years on elderly cataract risk were observed, particularly indicating a higher risk among women who experienced childhood famine compared to men with similar exposure.

Conclusion

Famine exposure during the early stages of life is associated with a heightened risk of developing cataracts in old age. To prevent cataracts in elderly individuals, particularly in females, measures should be taken to address nutritional deficiencies in these specific periods.

Upregulation of EphA2 is associated with apoptosis in response to H2O2 and UV radiation-induced cataracts

In this article, we examine the role of erythropoietin-producing hepatocellular receptor A2 (EphA2) in the apoptosis of lens epithelial cells (LECs) in H2O2 and UV radiation-induced cataracts. We treated SRA01/04 cells with H2O2 or ultraviolet (UV) radiation to create a cataract cell model. We constructed a cataract lens model by exposing mice to UV radiation. We used CCK8 assays, Annexin V-FITC analysis, and immunohistochemical staining to explore proliferation and apoptosis of the cataract model. Thereafter, we used quantitative real-time PCR (qPCR) analysis, Western blot assays, and immunofluorescence to determine gene and protein expression levels. We also employed Crispr/Cas9 gene editing to create an EphA2 knockout in SRA01/04 cells. Results: H2O2 or UV radiation induced SRA01/04 cells showed EphA2 gene upregulation. CCK8 and apoptosis assays showed that EphA2 over-expression (OE) reduced epithelial cell apoptosis, but knockout of EphA2 induced it in response to H2O2 and UV radiation, respectively. Mutation of the EphA2 protein kinase domain (c.2003G > A, p. G668D) had a limited effect on cell apoptosis. In vivo, the EphA2 protein level increased in the lenses of UV-treated mice. Our results showed that EphA2 was upregulated in SRA01/04 cells in response to H2O2 and UV radiation. Mutation of the EphA2 protein kinase domain (c.2003G > A, p. G668D) had a limited effect on H2O2 and UV radiation-induced cell apoptosis. We confirmed this change with an experiment on UV-treated mice. The present study established a novel association between EphA2 and LEC apoptosis.

The second extracellular domain of connexin 50 is important for in cell adhesion, lens differentiation, and adhesion molecule expression

Connexin (Cx)-forming channels play essential roles in maintaining lens homeostasis and transparency. We showed here channel-independent roles of Cx50 in cell-cell adhesion and confirmed the second extracellular (E2) domain as a critical domain for cell adhesion function. We found that cell adhesion decreased in cells expressing chimeric Cx50 in which the E2 domain was swapped with the E2 domain of either Cx43 or Cx46. In contrast, adhesion increased in cells expressing chimeric Cx43 and Cx46 with the Cx50 (E2) domain. This function is Cx channel-independent and Cx50 E2 domain-dependent cell adhesion acting in both homotypic and heterotypic manners. In addition, we generated eight site mutations of unique residues between Cx50 and the other two lens Cxs and found that mutation of any one of the residues abolished the adhesive function. Moreover, expression of adhesive-impaired mutants decreased adhesion-related proteins, N-cadherin and β-catenin. Expression of the adhesion-impaired Cx50W188P mutant in embryonic chick lens caused enlarged extracellular spaces, distorted fiber organization, delayed nuclear condensation, and cortical cataracts. In summary, the results from both in vitro and in vivo studies demonstrate the importance of the adhesive function of Cx50 in the lens.

Recent progress and research trend of anti-cataract pharmacology therapy: A bibliometric analysis and literature review

Cataract is the leading cause of blindness worldwide. Cataract phacoemulsification combined with intraocular lens implantation causes great burden to global healthcare, especially for low- and middle-income countries. Such burden would be significantly relieved if cataracts can effectively be treated or delayed by non-surgical means. Excitingly, novel drugs have been developed to treat cataracts in recent decades. For example, oxysterols are found to be able to innovatively reverse lens clouding, novel nanotechnology-loaded drugs improve anti-cataract pharmacological effect, and traditional Chinese medicine demonstrates promising therapeutic effects against cataracts. In the present review, we performed bibliometric analysis to provide an overview perspective regarding the research status, hot topics, and academic trends in the field of anti-cataract pharmacology therapy. We further reviewed the curative effects and molecular mechanisms of anti-cataract drugs such as lanosterol, metformin, resveratrol and curcumin, and prospected the possibility of their clinical application in future.

REPS2 downregulation facilitates FGF-induced adhesion and migration in human lens epithelial cells through FAK/Cdc42 signaling and contributes to posterior capsule opacification

Posterior capsular opacification (PCO) can cause postoperative visual loss after cataract surgery. Residual human lens epithelial cell (HLEC) proliferation, migration, epithelial-mesenchymal transition (EMT) and synthesis of extracellular matrix (ECM) are the entitative reasons for PCO. Low expression of Ral-binding protein 1-associated Eps domain-containing 2 (REPS2) and high levels of basic fibroblast growth factor (b-FGF) were observed in the lens and postoperative aqueous humor of cataract patients. REPS2 was identified as a negative regulator in growth factor signaling; however, its function in HLECs is unknown. This was first investigated in the present study by evaluating REPS2 expression in anterior lens capsules from cataract patients, a mouse cataract model, and HLE-b3 cells. The biological function of REPS2 in HLE-B3 cells was assessed by REPS2 silencing and Cell Counting Kit 8, wound healing, Transwell migration, F-actin staining, G-protein pulldown and western blot assays. In the present study, REPS2 was significantly downregulated in human and mouse cataract capsules and H₂O₂-treated HLE-B3 cells. REPS2 knockdown increased fibronectin, type I collagen, and α-smooth muscle actin expression levels and stimulated HLECs proliferation and migration; these effects were enhanced by FGF treatment and accompanied with focal adhesion kinase (FAK) phosphorylation, cell division cycle 42 (Cdc42) activation, focal adhesion protein upregulation, and F-actin cytoskeleton reorganization. However, treatment with the FAK inhibitor PF573228 abolished these effects. Thus, REPS2 downregulation in cataract HLECs induces their proliferation and facilitates FGF-induced ECM synthesis, EMT, cell adhesion and migration by activating FAK/Cdc42 signaling, which may underlie PCO pathogenesis.

EphA2 inhibits SRA01/04 cells apoptosis by suppressing autophagy via activating PI3K/Akt/mTOR pathway

This study attempted to determine the effect of EphA2 on H₂O₂-treated lens epithelial cells (SRA01/04) and the underlying mechanisms. MTT assay and flow cytometry were performed to assess cell viability and cell apoptosis. Western blot was carried out to examine the levels of proteins associated with apoptosis and autophagy. Our results revealed that EphA2 significantly elevated the reduced cell viability, and inhibited the increased cell apoptosis in H₂O₂-treated SRA01/04 cells, along with the significant up-regulated Bcl-2 and down-regulated Cleaved-caspase-3 and Bax protein levels, but which were all abolished by Rapa (autophagy activator). We also found that EphA2 significantly suppressed cell autophagy in H₂O₂-treated SRA01/04 cells. Additionally, EphA2 significantly up-regulated the protein levels of p-Akt and p-mTOR in H₂O₂-treated SRA01/04 cells, and the inhibition of Akt by MK-2206 and inhibition of mTOR by Rapa both obviously reversed EphA2-mediated the inhibition of autophagy in H₂O₂-treated SRA01/04 cells. In summary, these data demonstrated that EphA2 inhibited the apoptosis of SRA01/04 cells by inhibiting autophagy via activating PI3K/Akt/mTOR pathway.

Mutation of the EPHA2 Tyrosine-Kinase Domain Dysregulates Cell Pattern Formation and Cytoskeletal Gene Expression in the Lens

Genetic variations in ephrin type-A receptor 2 (EPHA2) have been associated with inherited and age-related forms of cataract in humans. Here, we have characterized the eye lens phenotype and transcript profile of germline Epha2 knock-in mutant mice homozygous for either a missense variant associated with age-related cataract in humans (Epha2-Q722) or a novel insertion-deletion mutation (Epha2-indel722) that were both located within the tyrosine-kinase domain of EPHA2. Confocal imaging of ex vivo lenses from Epha2-indel722 mice on a fluorescent reporter background revealed misalignment of epithelial-to-fiber cell meridional-rows at the lens equator and severe disturbance of Y-suture formation at the lens poles, whereas Epha2-Q722 lenses displayed mild disturbance of posterior sutures. Immunofluorescent labeling showed that EPHA2 was localized to radial columns of hexagonal fiber cell membranes in Epha2-Q722 lenses, whereas Epha2-indel722 lenses displayed disorganized radial cell columns and cytoplasmic retention of EPHA2. Immunoprecipitation/blotting studies indicated that EPHA2 formed strong complexes with Src kinase and was mostly serine phosphorylated in the lens. RNA sequencing analysis revealed differential expression of several cytoskeleton-associated genes in Epha2-mutant and Epha2-null lenses including shared downregulation of Lgsn and Clic5. Collectively, our data suggest that mutations within the tyrosine-kinase domain of EPHA2 result in lens cell patterning defects and dysregulated expression of several cytoskeleton-associated proteins.

Genotype, Age, Genetic Background, and Sex Influence Epha2-Related Cataract Development in Mice

Purpose

Age-related cataract is the leading cause of blindness worldwide. Variants in the EPHA2 gene increase the disease risk, and its knockout in mice causes cataract. We investigated whether age, sex, and genetic background, risk factors for age-related cataract, and Epha2 genotype influence Epha2-related cataract development in mice.

Methods

Cataract development was monitored in Epha2+/+, Epha2+/-, and Epha2-/- mice (Epha2Gt(KST085)Byg) on C57BL/6J and FVB:C57BL/6J (50:50) backgrounds. Cellular architecture of lenses, endoplasmic reticulum (ER) stress, and redox state were determined using histological, molecular, and analytical techniques.

Results

Epha2-/- and Epha2+/- mice on C57BL/6J background developed severe cortical cataracts by 18 and 38 weeks of age, respectively, compared to development of similar cataract significantly later in Epha2-/- mice and no cataract in Epha2+/- mice in this strain on FVB background, which was previously reported. On FVB:C57BL/6J background, Epha2-/- mice developed severe cortical cataract by 38 weeks and Epha2+/- mice exhibited mild cortical cataract up to 64 weeks of age. Progression of cataract in Epha2-/- and Epha2+/- female mice on C57BL/6J and mixed background, respectively, was slower than in matched male mice. N-cadherin and β-catenin immunolabeling showed disorganized lens fiber cells and disruption of lens architecture in Epha2-/- and Epha2+/- lenses, coinciding with development of severe cataracts. EPHA2 immunolabeling showed intracellular accumulation of the mutant EPHA2-β-galactosidase fusion protein that induced a cytoprotective ER stress response and in Epha2+/- lenses was also accompanied by glutathione redox imbalance.

Conclusions

Both, Epha2-/- and Epha2+/- mice develop age-related cortical cataract; age as a function of Epha2 genotype, sex, and genetic background influence Epha2-related cataractogenesis in mice.

Low Use of Ocular Sun Protection among Agricultural Workers in South Africa: Need for Further Research

Although ocular diseases related to solar ultraviolet radiation exposure have a high prevalence in Africa, little is known about the occupational use of ocular photoprotective measures on the continent. In a survey of South Africa farmworkers on a farm in the Limpopo Province, we analyzed factors related to ocular sun protection including use of different types of hats and sunglasses in relation to age, gender and duration of agricultural employment. Majority of participants (80%) never wore sunglasses while 23% never wore a hat when working. More male workers used measures to protect their eyes than female workers. The type of hat most worn was a cap although broad-brimmed hats provide more effective photoprotection. The need for awareness campaigns that focus on the importance of using photoprotective measures in both an agricultural and South Africa contexts was identified.

Association of Age-Related Cataract With Skin Cancer in an Australian Population

Purpose

Ultraviolet radiation from sunlight contributes to age-related cataract and skin cancer. The EPHA2 gene is implicated in both these diseases. The purpose of this study was to determine whether age-related cataract and skin cancer are associated in a cohort of older Australians.

Methods

A cross-sectional study was performed using the Historical Cohort of the Registry of Senior Australians. Individuals aged ≥65 years or aged ≥50 years and of Aboriginal or Torres Strait Islander descent, who had an aged care eligibility assessment between July 2005 and June 2015, and had a history of cataract surgery and/or skin cancer according to the Australian Government Medicare Benefits Schedule dataset, during the 3-year period prior, were evaluated (N = 599,316). A multivariable logistic regression model was used to determine association and multiple hypothesis correction was employed.

Results

Of the evaluated individuals, 87,097 (14.5%) had a history of cataract and 170,251 (28.4%) a history of skin cancer. Among those with a history of cataract, 20,497 (23.5%), 1127 (1.3%), and 14,730 (16.9%) individuals had a concurrent history of keratinocyte, melanoma, and premalignant/solar keratosis, respectively. Those with a history of cataract were 19% more likely to have a history of skin cancer (odds ratio [OR], 1.19; 95% confidence interval [CI], (1.17–1.21). Co-occurrence of keratinocyte skin cancer was 16% (OR, 1.16; 95% CI, 1.14–1.18), melanoma 21% (OR, 1.21; 95% CI, 1.13–1.29), and premalignant/solar keratosis 19% (OR, 1.19; 95% CI, 1.17–1.22) more in the presence than absence of history of cataract.

Conclusions

Age-related cataract is positively associated with skin cancer and its subtypes, including premalignant lesions in an older Australian population.